One thousand three hundred and fifty one strains of Shigella sonnei isolated mainly in Nagasaki and Saga prefectures within a year from May 1965, were subjected to the colicine typing. All strains were tested by Naito's method, and 109 of them were tested by Abott and Shannon's method in parallel.
The test by Naito's method revealed that B2 was an absolutely predominant type over all occasions except one caused by subtype C1. On the other hand, by Abbott and Shannon's method it became obvious that some outbreaks and some districts were predominated by Type 6, 6/11, and 11, though type 4, 4/14, and 14 were prevailing over vast majority of the occasions.
So, from epidemiological viewpoint, it should be admitted at this stage that Abbott and Shannon's method is more valuable than Naito's method.
Besides these experiments, typing of 30 strains originated from Taiwan, Hongkong, Korea, and the Philippines, of 74 stock cultures isolated in Nagasaki prefecture in 1959, and of 2 standard strains of Shigella sonnei was performed by the both methods. It is noteworthy that Abbott and Shannon's Type 9, which can not be enrolled in Naito's classification prevails in Hongkong
The relation between each type classifiable by the both methods was also discussed in this paper.
